Hostname: page-component-cd9895bd7-gxg78 Total loading time: 0 Render date: 2024-12-18T19:03:20.820Z Has data issue: false hasContentIssue false

Oscillations over basins of variable depth

Published online by Cambridge University Press:  21 April 2006

G. R. Ghanimati
Affiliation:
Department of Mechanical Engineering, University of California, Berkeley, CA 94720, USA
P. M. Naghdi
Affiliation:
Department of Mechanical Engineering, University of California, Berkeley, CA 94720, USA

Abstract

This paper is concerned with oscillations of a body of water in basins of variable depth, employing a system of linearized equations which can be obtained from the theory of a directed fluid sheet for an incompressible, homogeneous, inviscid fluid (Green & Naghdi 1976a, 1977). For free oscillations over a level bottom, an assessment of the range of validity of the linearized theory is made by an appropriate comparison with a corresponding well-known exact solution (Lamb 1932). This assessment indicates an ‘intermediate’ range of validity for the linearized theory not covered by usual classical approximations for long waves. Encouraged by this assessment, we apply the linear theory of a directed fluid sheet to basins of variable depth; and, in particular, consider a class of basin profiles whose equilibrium depth (along its width) varies in one direction only. By a method of asymptotic integration, a general solution is obtained which is relatively simple and accounts for the effect of vertical inertia. The solution is sinusoidal in time, periodic along the breadth direction and involves Bessel functions of the first order in the width direction. For two special basin profiles, detailed comparisons are made between the predictions of the asymptotic solution (i.e. the frequencies in the lowest modes of oscillations) with corresponding results obtained by other procedures.

Type
Research Article
Copyright
© 1986 Cambridge University Press

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

References

Abramowitz, M. & Stegun, I. A. (eds) 1965 Handbook of mathematical functions with formulas, graphs and mathematical tables. New York: Dover.
Benjamin, T. B., Bona, J. L. & Mahony, J. M. 1972 Model equations for nonlinear dispersive systems. Phil. Trans. R. Soc. Lond. A 272, 4778.Google Scholar
Csanady, G. T. 1975 Hydrodynamics of large lakes. Ann. Rev. Fluid Mech. 7, 357388.Google Scholar
Green, A. E., Laws, N. & Naghdi, P. M. 1974 On the theory of water waves. Proc. R. Soc. Lond. A 338, 4355.Google Scholar
Green, A. E. & Naghdi, P. M. 1976a Directed fluid sheets. Proc. R. Soc. Lond. A 347, 447473.Google Scholar
Green, A. E. & Naghdi, P. M. 1976b A derivation of equations for wave propagation in water of variable depth. J. Fluid Mech. 78, 237246.Google Scholar
Green, A. E. & Naghdi, P. M. 1977 Water waves in a nonhomogeneous incompressible fluid. J. Appl. Mech. 44, 523528.Google Scholar
Greenhill, A. G. 1887 Wave motion in hydrodynamics. Am. J. Math. 9, 62111.Google Scholar
Kirchhoff, G. 1879 Ueber stehende Schwingungen einer schweren Flüssigkeit. Mber. Akad. Wiss. Berlin, pp. 395410.Google Scholar
Kirchhoff, G. 1880 Ann. Phys. Chem., N.F. 10 (246), 34–16.
Korteweg, D. J. & De Vries, G. 1895 On the change of form of long waves advancing in a rectangular channel and on a new type of long stationary waves. Phil. Mag. 39 (5), 422–443.Google Scholar
Lamb, H. 1932 Hydrodynamics, 6th edn. Cambridge University Press.
Langer, R. E. 1935 On the asymptotic solution of ordinary differential equations with reference to the Stoke's phenomenon about a singular point. Trans. Am. Math. Soc. 37, 397416.Google Scholar
Meyer, R. E. & Parter, S. V. 1980 Singular Perturbations and Asymptotics. New York: Academic Press.
Miles, J. 1985 Surface waves in basins of variable depth. J. Fluid Mech. 152, 379389.Google Scholar
Naghdi, P. M. 1957 The effect of transverse shear deformation on the bending of elastic shells of revolution. Q. Appl. Maths. 15, 4152.Google Scholar
Sen, B. M. 1927 Waves in canals and basins. Proc. Lond. Math. Soc. (2) 26, 363376.Google Scholar
Storchi, E. 1949 Legame fra la forma del pelo libero e quella recipiente nelle oscillazioni di un liquido. 1st Lombardo Sci. Lett. Bend. Cl. Mat. Nat. (3) 13 (82), 95–112.Google Scholar
Storchi, E. 1952 Piccole oscillazioni dell'acqua contenuta da pareti piane. Atti Accad. Naz. Lincei, Rend. Cl. Sci. Fis. Mat. Nat. (8) 12, 544552.Google Scholar
Wehausen, J. V. & Laitone, E. V. 1960 Surface waves. In Handbuch der Physik, vol. 9, pp. 445–778.
Wilson, B. W. 1972 Seiches. In Advances in Hydrodynamic Science, pp. 1–94. Academic Press.